> Parr III..Srcr. iii. §2] CRETACEOUS. 893 
regarded by Dr. Barrois as equally distinct on the English side of the 
Channel in the form of surfaces of hardened and corroded chalk. One 
of these surfaces marks the upper limit of the Micraster group on the 
Sussex coast, where it consists of a band of yellowish hardened and 
corroded chalk about six inches thick, containing rolled green-coated 
nodules of chalk.! A similar hardened, corroded, tubular band forms 
the same limit in the Isleof Thanet. Among the fossils of the Micraster 
division the following may be mentioned: Micraster cor-testudinarium, 
M. cor-anguinum, Cidaris clavigera, Echinocorys gibbus, Echinoconus conicus, 
Epiaster gibbus, Terebratulina gracilis, Terebratula semiglobosa, Ostrea 
vesicularis, Inoceramus involutus. 
The middle division, or Margate chalk, has been named the Marsupite 
zone by Dr. Barrois from the abundance of these crinoids. It attains a 
thickness of about 80 feet in the Isle of Thanet, where it contains few or 
no flints, and upwards of 400 feet in the Hampshire basin, where flints 
_ arenumerous. Among its fossils are Amorphospongia globosa, Bourgueti- 
_ erinus ellipticus, Marsupites ornatus, M. Milleri, Micraster cor-anguinum, 
Fichinoconus conicus, Hchinocorys gibbus, Cidaris clavigera, C. sceptrifera, 
Thecideum Wetherelli, Terebratula semiglobosa, Rhynchonella plicatilis, Tere- 
bratulina striata, Spondylus (Lima) spinosus, S. dutempleanus, Pecten cretosus, 
Osirea vesicularis, O. hippopodium, Inoceramus lingua (and several others), 
Belemnites verus, B. Merceyi, Ammonites leptophyllus. 
The highest remaining group, or Norwich chalk, forms the Belemnitella 
zone so well marked in northern Europe. It attains a thickness of from 
100 to 160 feet in the Hampshire basin (Portsdown Chalk), is absent from 
that of London, but reappears in Norfolk, where it attains its greatest de- 
velopment. It is at Norwich a white crumbling chalk with layers of. 
black flints. Among its fossils are Parasmilia centralis, Trochosmilia laxa, 
Cyphosoma magnificum, Salenia geomeirica, Echinocorys ovatus, Rhynchonella 
octoplicata, R. limbata, Terebratula carnea, T. obesa, Ostrea lunata, Belemnitella 
mucronata, B. quadrata. 
The uppermost division, or Danian, of the Continental chalk appears 
-to be absent in England, unless its lower portions are represented by 
some of the uppermost beds of the Norwich chalk. 
The Cretaceous system is sparingly represented in Ireland and Scotland. 
Under the Tertiary basaltic plateau of Antrim there les an interesting 
series of deposits which in lithological aspect differ greatly from their 
English equivalents, and yet from their fossil contents can be satisfac- 
torily paralleled with the latter. They are thus arranged :? 

Hard white limestone 65 to 100 feet = zone of Belemnitella mucro- 
nata. eee 
glee Ps WB ie ot 8 LG ape hie . Marsupites. BS 
Chloritic chalk Siiatirw Gare »,  Micrasters 
Chloritic sand and »,  Holaster planus. Bo 
sandstone Shots UD sos » Terebratulina gracilis.( 5 5 
. 5 
OQ 
_ Grey marls and yellow Be 
sandstones Dares, Sete iby »  Holaster subglobosus. ) &°S 
Glauconitic sand Oiveen HD be 3 ») .. Fecten asper. es 
————— —— = 

' Barrois, Terrain Crétacé de ? Angleterre, &c., 1876, p. 21. 
2 Barrois, Op. cit. p. 216. 
